This invention is concerned with a method of controlling the progressive operation of a tool along a predetermined path in relation to a selected portion of a workpiece, wherein at least one operating parameter relating to the operation of the tool can be varied during the progressive operation thereof.
The invention is further concerned with machines for operating progressively along e.g. marginal portions of shoes using a rotary tool, wherein at least one operating parameter relating to the operation of the tool can be varied during the progressive operation thereof.
By way of example only, there is described in EP-A-0 079 695 the U.S. equivalent being U.S. Pat. No. 4,452,057 a machine suitable for use in performing a progressive operation along marginal portions of shoes comprising a shoe support, a tool carrier for supporting a rotary tool, drive means for effecting rotation of such tool, first and second n.c. motor means for effecting relative movement, both lengthwise and widthwise of a shoe supported by the shoe support, between the shoe support and the tool carrier, and third n.c. motor means for controlling the heightwise position of the tool carrier relative to the shoe support, as relative lengthwise and widthwise movement is caused to take place therebetween, each such motor means operating under control of computer control means by which drive signals are generated and supplied to said motor means in accordance with a programmed instruction, including digitised coordinate axis values, using three coordinate axes, for a plurality of selected points along the marginal portion of the or a similar shoe, so that, in an operating mode of the machine, the tool carrier can follow a predetermined path, determined according to the contour of the shoe portion being operated upon, relative to the shoe support, and a tool carried by the tool carrier can thus be caused to operate progressively along a marginal portion of a shoe supported by the shoe support, the machine further comprising path-determining means operable in a path-determining mode of the machine and comprising a control device for causing relative movement to take place along said three coordinate axes between the shoe support and tool carrier to bring them to successive selected points along the marginal portion of such shoe, together with means for digitising, and storing in digitised form, the coordinate axis values of each such selected point. (By "n.c. motor means" where used herein is to be understood means comprising at least one n.c. motor, i.e. a motor the operation of which is controlled by control signals supplied thereto in accordance with digitised information appropriate to the desired operation of the motor. Examples of such motors are stepping motors and d.c. servo motors.)
In such machine, which, as described, is a machine for performing a progressive roughing operation on marginal portions of shoe bottoms, the speed of rotation of the tool remains unchanged during a cycle of operation. It will, however, be appreciated that as the tool progresses along different sections of the marginal portions of a shoe bottom, different operating parameters may be required in order to ensure a uniform degree of roughing of the whole of the marginal portions. For example, the upper may be made of different materials in different regions of the shoe and the different materials may well be more or less sensitive to the action of the roughing tool. It has been the practice over a number of years to vary in pre-selected regions of the marginal portions of the shoe bottom, the roughing pressure, i.e. the pressure by which the roughing tool is urged against the shoe bottom. In general, however, the sections have been pre-defined and not readily alterable, so that the applied pressure could not always be set appropriately to the sensitivity of the material being roughed. This therefore led to compromises in the roughing quality.
Similarly, there is described in EP-A-0 351 993 a machine for performing a progressive adhesive-applying operation to selected portions of components, e.g. shoes, wherein, in the same manner as described with reference to the aforementioned roughing machine, n.c. motor means is provided for effecting relative movement along three coordinate axes, between a shoe support and tool supporting means of said machine. In the adhesive-applying machine, moreover, the tool is an adhesive-applying tool incorporating a rotary brush assembly, means being provided for supplying adhesive to the adhesive-applying tool.
In such machine the rotary brush assembly is caused to rotate during the adhesive-applying operation firstly so that it spreads the adhesive over the area to be subsequently bonded and secondly so that it has a "scrubbing" effect which assists penetration of the adhesive into the material of the shoe upper. In said machine, furthermore, the speed of rotation of the brush assembly is pre-defined and cannot be altered during the machine cycle of operation. With different shoe upper materials, however, it has been found that the optimum speed of rotation of the brush assembly varies so that in using a single pre-defined speed for applying adhesive to shoes having uppers made of different materials compromise is frequently necessary.